The 21-year-old admitted the person in the video, posted moments before the draft, was him but said the incident occurred "several years ago".

"I made a mistake, a huge mistake," said the highly rated offensive lineman, who played for the University of Mississippi.

However Tunsil said he does not have a drug problem, adding: "You can check all my college tests. I never failed one."

Dolphins general manager Chris Grier said the team were "very comfortable" with the information they had on Tunsil, having completed background checks.

CBSSports.com national columnist Bill Reiter said the situation threatened to overshadow the draft.

"The internet - one of the few things bigger than the NFL - hijacked the NFL draft on Thursday, turning a celebration of the game into a real-time soap opera involving drug use, accusations of pay-for-play shenanigans, the freefall of the player involved, and one bizarre press conference," he wrote.

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Who went where on NFL Draft day one?

Goff goes first

The Los Angeles Rams, who have relocated from St Louis, traded with the Tennessee Titans to secure the top pick.